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Research in Astronomy and Astrophysics 2024年第2期24卷 74-82页

作者： P.Vemareddy Jorn Warnecke Ph.A.Bourdin Indian Institute of Astrophysics Sarjapur roadII BlockKoramangalaBengaluru-560034India Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3D-37077 GöttingenGermany Institute of Physics University of GrazUniversitätsplatz 5A-8010 GrazAustria

Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short timescales.As of now there exist no regular measurements of coronal magnetic fields,and therefore generating the coronal magnetic field evolution using observations of the magnetic field at the photosphere is a fundamental requirement to understanding the origin of transient phenomena from solar active regions(ARs).Using the magneto-friction(MF)approach,we aim to simulate the coronal field evolution in the solar AR 11429.The MF method is implemented in the open source PENCIL CODE along with a driver module to drive the initial field with different boundary conditions prescribed from observed vector magnetic fields at the photosphere.In order to work with vector potential and the observations,we prescribe three types of bottom boundary drivers with varying free-magnetic energy.The MF simulation reproduces the magnetic structure,which better matches the sigmoidal morphology exhibited by Atmospheric Imaging Assembly(AIA)images at the pre-eruptive time.We found that the already sheared field further driven by the sheared magnetic field will maintain and further build the highly sheared coronal magnetic configuration,as seen in AR 11429.Data-driven MF simulation is a viable tool to generate the coronal magnetic field evolution,capturing the formation of the twisted flux rope and its eruption.

关键词： sun corona-sun evolution-sun magnetic fields-sun photosphere

Variation in the Flaring Potential of Different sunspot Groups During Different Phases of Solar Cycles 23 and 24

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Research in Astronomy and Astrophysics 2024年第2期24卷 144-153页

作者： Abha Singh Anurag Chaudhari Gyaneshwar Sharma A.K.Singh Department of Physics T.D.P.G.College Jaunpur-222002India Department of Physics Banaras Hindu UniversityVaranasi-221005India

In this present study,we have analyzed different types of X-ray solar flares(C,M,and X classes)coming out from different classes of sunspot groups(SSGs).The data which we have taken under this study cover the duration of 24 yr from 1996 to 2019.During this,we observed a total of 15015 flares(8417 in SC-23 and 6598 in SC-24)emitted from a total of 33780 active regions(21746 in SC-23 and 12034 in SC-24)with sunspot only.We defined the flaring potential or flare-production potential as the ratio of the total number of flares produced from a particular type of SSG to the total number of the same-class SSGs observed on the solar surface.Here we studied yearly changes in the flaring potential of different McIntosh class groups of sunspots in different phases of SC-23 and 24.In addition,we investigated yearly variations in the potential of producing flares by different SSGs(A,B,C,D,E,F,and H)during different phases(ascending,maximum,descending,and minimum)of SC-23 and 24.These are our findings:(1)D,E,and F SSGs have the potential of producing flares≥8 times greater than A,B,C and H SSGs;(2)The larger and more complex D,E,and F SSGs produced nearly 80%of flares in SC-23 and 24;(3)The A,B,C and H SSGs,which are smaller and simpler,produced only 20%of flares in SC-23 and 24;(4)The biggest and most complex SSGs of F-class have flaring potential 1.996 and 3.443 per SSG in SC-23 and 24,respectively.(5)The potential for producing flares in each SSG is higher in SC-24 than in SC-23,although SC-24 is a weaker cycle than SC-23.(6)The alterations in the number of flares(C+M+X)show different time profiles than the alterations in sunspot numbers during SC-23 and 24,with several peaks.(7)The SSGs of C,D,E,and H-class have the highest flaring potential in the descending phase of both SC-23 and 24.(8)F-class SSGs have the highest flaring potential in the descending phase of SC-23 but also in the maximum phase of SC-24.

关键词： (sun:)sunspots-sun flares-sun activity-sun magnetic fields-sun filaments-prominences

Investigation on the Formation of Herringbone Structure in TypeⅡSolar Radio Bursts

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Research in Astronomy and Astrophysics 2023年第5期23卷 101-109页

作者： Z.Z.Abidin A.N.Zulkiplee V.Epin F.A.M.Pauzi Radio Cosmology Research Lab Physics Dept.Faculty of ScienceUniversity of MalayaKuala LumpurMalaysia

We report detailed observation of the“herringbone”of a Type II solar radio burst that occurred on 2010 November 3rd.Data from the Space Weather Prediction Center,National Oceanic and Atmospheric Administration,e-CALLISTO,and Nan?ay Radio Heliograph are analyzed.We determine the brightness temperature and degree of circular polarization of the“herringbone”burst.Correlations between the physical parameters and the“herringbone”are examined.Based on the relationship,this is the first study that suggested this“herringbone”was generated through fundamental plasma.

关键词： sun activity-sun corona-sun coronal mass ejections(CMEs)-sun magnetic fields-sun radio radiation

Solar Active Region Magnetogram Generation by Attention Generative Adversarial Networks

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Research in Astronomy and Astrophysics 2023年第2期23卷 47-52页

作者： Wenqing sun Long Xu Yin Zhang Dong Zhao Fengzhen Zhang State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Peng Cheng National Laboratory Shenzhen 518000China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China State Key Laboratory of Communication Content Cognition People’s Daily OnlineBeijing 100733China

Learning the mapping of magnetograms and EUV images is important for understanding the solar eruption mechanism and space weather forecasting.Previous works are mainly based on the pix2pix model for full-disk magnetograms generation and obtain good performance.However,in general,we are more concerned with the magnetic field distribution in the active regions where various solar storms such as the solar flare and coronal mass ejection happen.In this paper,we fuse the self-attention mechanism with the pix2pix model which allows more computation resource and greater weight for strong magnetic regions.In addition,the attention features are concatenated by the Residual Hadamard Production(RHP) with the abstracted features after the encoder.We named our model as RHP-attention pix2pix.From the experiments,we can find that the proposed model can generate magnetograms with finer strong magnetic structures,such as sunspots.In addition,the polarity distribution of generated magnetograms at strong magnetic regions is more consistent with observed ones.

关键词： techniques image processing-sun magnetic fields-sun general

Global Energetics of Solar Powerful Events on 2017 September 6

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天文和天体物理学研究:英文版 2023年第9期23卷 180-193页

作者： Dong Li Alexander Warmuth Jincheng Wang Haisheng Zhao Lei Lu Qingmin Zhang Nina Dresing Rami Vainio Christian Palmroos Miikka Paassilta Annamaria Fedeli Marie Dominique Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China Leibniz-Institut fur Astrophysik Potsdam(AIP) An der Sternwarte 16D-14482 PotsdamGermany Yunnan Observatories Chinese Academyof Sciences.Kunming 650216China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsCASBeijing 00049China Department of Physics and Astronomy University of TurkuTurku 20014Finland Solar-Terrestrial Centre of Excellence/SIDC Royal Observatory of Belgium3 Avenue CirculaireB-1180 UccleBelgium

Solar flares and coronal mass ejections(CMEs)are thought to be the most powerful events on the sun.They can release energy as high as~10^(32)erg in tens of minutes,and also can release solar energetic particles(SEPs)into interplanetary space.We explore global energy budgets of solar major eruptions that occurred on 2017 September 6,including the energy partition of a powerful solar flare,and the energy budget of the accompanying CME and SEPs.In the wavelength range shortward of~222 nm,a major contribution of the flare radiated energy is in the soft X-ray(SXR)0.1-7 nm domain.The flare energy radiated at wavelengths of Lyαand mid-ultraviolet is larger than that radiated in the extreme ultraviolet wavelengths,but it is much less than that radiated in the SxR waveband.The total flare radiated energy could be comparable to the thermal and nonthermal energies.The energies carried by the major flare and its accompanying CME are roughly equal,and they are both powered by the magnetic free energy in the NOAA AR 12673.Moreover,the CME is efficient in accelerating SEPs,and the prompt component(whether it comes from the solar flare or the CME)contributes only a negligible fraction.

关键词： sun flares-sun magnetic fields-sun coronal mass ejections(CMEs)

Application of a magnetic-field-induced Transition in Fe X to Solar and Stellar Coronal magnetic Field Measurements

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Research in Astronomy and Astrophysics 2023年第2期23卷 1-17页

作者： Yajie Chen Wenxian Li Hui Tian Xianyong Bai Roger Hutton Tomas Brage School of Earth and Space Sciences Peking UniversityBeijing 100871China Max Planck Institute for Solar System Research Gottingen D-37077Germany National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Department of Astronomy Beijing Normal UniversityBeijing 100875China Division of Mathematical Physics Lund UniversityPO Box 118sE-22100 LundSweden

magnetic fields play a key role in driving a broad range of dynamic phenomena in the atmospheres of the sun and other stars.Routine and accurate measurements of the magnetic fields at all the atmospheric layers are of critical importance to understand these magnetic activities,but in the solar and stellar coronae such a measurement is still a challenge due to the weak field strength and the high temperature.Recently,a magnetic-field-induced transition(MIT)of Fe X at 257.26A has been proposed for the magnetic field measurements in the solar and stellar coronae.In this review,we present an overview of recent progresses in the application of this method in astrophysics.We start by introducing the theory underlying the MIT method and reviewing the existing atomic data critical for the spectral modeling of Fe X lines.We also discuss the laboratory measurements that verify the potential capability of the MIT technique as a probe for diagnosing the plasma magnetic fields.We then continue by investigating the suitability and accuracy of solar and stellar coronal magnetic field measurements based on the MIT method through forward modeling.Furthermore,we discuss the application of the MIT method to the existing spectroscopic observations obtained by the Extreme-ultraviolet Imaging Spectrometer onboard Hinode.This novel technique provides a possible way for routine measurements of the magnetic fields in the solar and stellar coronae,but still requires further efforts to improve its accuracy.Finally,the challenges and prospects for future research on this topic are discussed.

关键词： sun corona-sun magnetic fields-sun UV radiation

Eruption of an Active-Region Filament Driven by an Emerging Bipole

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Chinese Journal of Astronomy and Astrophysics 2007年第1期7卷 129-140页

作者： Yun-Chun Jiang Yuan-Deng Shen Jing-Xiu Wang National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

A section of an S-shaped filament underwent an eruption in a sigmoidal active region （AR 8027） with S-shaped coronal structure, which was clearly driven by a bipole emerging below the NW end of the filament. The bipole with two separating poles showed typical characteristics of emerging flux region （EFR） and its axis rotated counterclockwise. Two canceiling magnetic features （CMFs） were formed between the two poles and adjacent flux with opposite polarity and substantial flux cancellation occurred in them. Along with the bipole emergence the filament was strongly disturbed. Just before the filament eruption, two X-ray loops overlying the filament brightened, an axial X-ray structure and then a cusp structure appeared. During the eruption first the whole filament rose and then its SE end broke away from the chromosphere, while its NW end remained stationary. Helical structure and motion were observed in the filament body and downward mass motion in the two ends. After the eruption, a major part of the filament remained and slowly returned to quiescence, and an X-ray arcade and an axial structure formed. These observations suggest that the eruption resuited from the interaction between the bipole and the overlying loops. We provide evidence that steady photospheric reconnection between their footprints took place in the two CMFs during the bipole emergence.

关键词： sun： filaments-sun flares-sun magnetic fields-sun corona-sun X-rays

A Comparison of Co-temporal Vector Magnetograms Obtained with HMI/SDO and SP/Hinode

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Research in Astronomy and Astrophysics 2023年第12期23卷 175-183页

作者： Mei Zhang Haocheng Zhang Chengqing Jiang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China High Altitude Observatory National Center for Atmospheric Research3080 Center Green DriveBoulderCO 80301USA Jericho High School 99 Cedar Swamp RoadJerichoNY 11753USA School of Space and Environment Beihang UniversityBeijing 100091China

Accurate measurement of magnetic fields is very important for understanding the formation and evolution of solar magnetic fields.Currently,there are two types of solar magnetic field measurement instruments:filter-based magnetographs and Stokes polarimeters.The former gives high temporal resolution magnetograms and the latter provides more accurate measurements of magnetic fields.Calibrating the magnetograms obtained by filter-based magnetographs with those obtained by Stokes polarimeters is a good way to combine the advantages of the two types.Our previous studies have shown that,compared to the magnetograms obtained by the Spectro-Polarimeter(SP)on board Hinode,those magnetograms obtained by both the filter-based Solar magnetic Field Telescope(SMFT)of the Huairou Solar Observing Station and by the filter-based Michelson Doppler Imager(MDI)aboard SOHO have underestimated the flux densities in their magnetograms and systematic center-to-limb variations present in the magnetograms of both instruments.Here,using a sample of 75 vector magnetograms of stable alpha sunspots,we compare the vector magnetograms obtained by the Helioseismic and magnetic Imager(HMI)aboard Solar Dynamics Observatory(SDO)with co-temporal vector magnetograms acquired by SP/Hinode.Our analysis shows that both the longitudinal and transverse flux densities in the HMI/SDO magnetograms are very close to those in the SP/Hinode magnetograms and the systematic center-to-limb variations in the HMI/SDO magnetograms are very minor.Our study suggests that using a filter-based magnetograph to construct a low spectral resolution Stokes profile,as done by HMI/SDO,can largely remove the disadvantages of the filter-type measurements and yet still possess the advantage of high temporal resolution.

关键词： The sun-sun magnetic fields-sun photosphere-(sun:)sunspots